/*#include<bits/stdc++.h>
using namespace std;
int main()
{
/*	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	pair<int,int>p1={3,4};
	int x=p1.first;
	int y=p1.second;
	
*/

/*	vector<int> v1(5,0);
	vector<int> v2={1,2,3,4,5};
*/
/*
	map<int,int> cnt;
	int arr[]={1,2,2,3,3,3};
	for(auto it:arr)
	{
		cnt[it]++;
	}	
	
	for(auto&p:cnt)
	{
		int key=p.first;
		int val=p.second;
		cout<<key<<":"<<val;
		}	
	return 0;
}*/

/*#include<bits/stdc++.h>
using namespace std;
int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
  vector<int> v(1e5,0);
  int n;
  cin>>n;
  map<int,int> cnt;
  for(int i=0;i<n;i++)
  {
    cin>>v[i];
    cnt[v[i]]++;
  }

int add=0;
  for(auto it:cnt)
  {
    int key=it.first;
    int val=it.second;
    if(val<key) add+=val;
    if(val>key) add+=val-key;
  }
  cout<<add;
  return 0;
}*/



#include<bits/stdc++.h>
using namespace std;
int main()
{
  ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
  int n,m;
  cin>>n>>m;
  vector<vector<int>> vv(n+1,(vector<int>(m+1,0)));
  int t;
  cin>>t;
  for(int i=1;i<=t;i++)
  {
    int x,y;
    cin>>x>>y;
    vv[x][y]=1;
  }

  int dirs[4][2]={{-1,0},{1,0},{0,-1},{0,1}};

  int k;
  cin>>k;
  for(int minute=1;minute<=k;minute++)
  {
      vector<vector<int>> nvv=vv;
      for(int i=1;i<=n;i++)
      {
        for(int j=1;j<=m;j++)
        {
          if(vv[i][j]==1)
          {
            for(auto it:dirs)
            {
              int ni=i+it[0];
              int nj=j+it[1];
              if(ni>=1&&ni<=n&&nj>=1&&nj<=m)
              {
                nvv[ni][nj]=1;
              }
            }
          }
        }
      }
      vv=nvv;
  }

  int ans=0;
  for(int i=1;i<=n;i++)
  {
    for(int j=1;j<=m;j++)
    {
      if(vv[i][j]==1)
      {
          ans++;
      }
    }
  }
 
  cout<<ans;
  
  return 0;
}
